(1) Field of the Invention
The present invention relates to a method for preventing hydrogen embrittlement in metals and alloys.
(2) Description of the Prior Art
Heretofore, it has been well known that in welding, casting, rolling and the like of a metal or alloy, hydrogen atoms diffuse into the metal and variations in its mechanical properties, such as crack, breakage and the like occur, which is a commercial problem known as "hydrogen embrittlement". In order to prevent this hydrogen embrittlement, there is only one process wherein hydrogen is diffused and exhaled through thermal annealing (heating) but this process is not fully satisfactory for the prevention of hydrogen embrittlement. In particular, breakage due to hydrogen embrittlement still occurs at welded portions of large plants and in nuclear reactor fuel cladding (Zircaloy). Sudden breakage of a cast metal or alloy is presumably caused by to the progress of a slight break or crack due to the diffusion and aggregation of the residual hydrogen, and as a method for preventing such hydrogen embrittlement, there has been no process other than thermal annealing. In order to save energy reduction of the thermal annealing time is desired and a method for removing hydrogen from electrolytically refined copper or a cast, a welded portion and the like has been demanded.